Process for the preparation of nitrocellulose.



0. SGHNIT ER. I PBOGESS FOR THE PREPARATION OF HITROOELLULOSE. APPLIOATIOH FILED BAR. 18, 1913.

Patent ed Apr. 14, 1914 with explosive rapidityresulting in eon-.

I UNITED STATES PATENT OFFICE.

KARL SCHNITER, oF'FRANKFoRT-oN-THE-Mh-N, GERMANY. ASSIGNOR to THE FIRM OF VEREIN-IGTE KUNSTSEIDEFAJBRIKEN A, e., OF.-KELSTERBACH-QN-THE-MAIN,

GERMANY.

rnocnss FOR THE PREPARATION or NIITROCE'LLULOSE.

Specification 0'! Letters Patent. Patented Apr, 14, 1914, Application filed March 18, 1913. 7 Serial No. 755,129.

i To all whom it may concern Be-it known that I, KARL SQHNITER', citizen of Switzerland, residing at Frankforton-the-M-ain, Germany. have inventetL certain new and useful Improvements in Processes'for the Preparation of Nitrocellulose of which the following is a specification.

N'tro-cellulose prepared by treating cellulose with -nitric acid. or a mixture of nitric and sulfuric acids. It has hitherto not been possible to prevent the charge i. c. the mixture of nitro-eellulosc and acid) from occasionally tal'iii'ig fire. ln unfavorable cases, more particularly \vhen the nitrocellulose is already freed from the greater part; of the acid. the combustion takes place siderable damage to the apparatus and to the lmildine'. It has been attempted to control this ditliculty by \vashin; the charge with other ncid mixtures but it has not proved possible to overcome the dilliculty in this way.

According to the present invention combustion of the clmrge is entirely prevented bv wishing the nitro-cellulose immediatelv after the nitration has been effected. with cooled acid. which treatment prevents combnstion Without in any other respect acting on the nit'rated material. The cooled waste acid from a previous operation prel'erablv used. and in this manner the material is lowered to a'temperatnre at which spontaneous decomposition is mayle impo.--:sible,

It has heretofore been proposed to infincn e the nitration itself by' fresh and cold acid. However, even under these conditions, combustion ofthe charge occnrs occasionally. According to the present invention ht nvever. combustion of the charge is entirely obviated by washing the nitro-cellulose with cooled acid after the nitration has taken place.

In order to carry' out the nitration an apparatus is employed which is built on the principle of the continuously circulating dye bath. The apparatus is shown in section in the accompanying drawing.

u. is a vessel provided with a removable lid, in which vessel the nitration takes place. An outflow pipe 6 is provided he:

unchanged.

low leading to a. pump 0, from: which a pipe cpasses to discharge the liquid into tie cells d, arranged within the vessel (1., containing the material to be nitrated. The

bottoms e of these cells are perforated. The' apparatus is resistant to acid and does not;

allow the acid to escape. When the pump 0 is started the acid from the vessel (1 is. forced by the pump through the pipe 0 on to the cotton in the cells, penetrates therethrou'h and-runs back into the vessel 41 through t e. perforated bottoms e, the circulation ofacid being continued while the pump is in operation. \Vhen the nitration is completed, the nump'o is shut off and the acid in the cells (I is allowed to run off. 'As soon as this is done, the cooled acid from an earlier operation is alloived to .drop from a second container'f over the nitrated material until .70 the latter has been sufficiently cooled. The material is then centrifugalized from the acid and further treated in the usual man ner.

' What I claim as my invention is:

1. The herein described method of preparing, Intro-cellulose. which consists in i completely nitrating cellulose in a single bath of nitrating acid. and thereafter subjecting'the nit rated cellulose to a bath of a similar acid at a. lower temperature than that of the acid first employed, under such conditions that said nitrated cellulose is cooled and its chemical-constitution remains- 2. The herein described method of pre-' paring nit-ro-cellulose, which consistsin completely nitrating cellulose in a single bath of nitrating acid and thereafter subjecting the nitrated cellulose to a bath of cooled waste acid from the first bath, under such conditions that sz'iid nitrated cellitlose is cooledand its chemical constitution remains unchanged.

In testimony whereof I aflix my signature in presence of witnesses,-

, 1 DR, K.'.SCHNITER.

Vitnesses:

' PEMSCL M. Lone,

H R ANN Purser) MANrn'nn Lone.- 

